diff --git a/bin/sessionmgr/story/model/BUILD.gn b/bin/sessionmgr/story/model/BUILD.gn
index 6d6dfef..cb0518f 100644
--- a/bin/sessionmgr/story/model/BUILD.gn
+++ b/bin/sessionmgr/story/model/BUILD.gn
@@ -60,6 +60,7 @@
 
   public_deps = [
     "//peridot/public/fidl/fuchsia.modular.storymodel",
+    "//peridot/public/lib/fostr/fidl/fuchsia.modular.storymodel",
   ]
 
   deps = [
diff --git a/bin/sessionmgr/story/model/apply_mutations.cc b/bin/sessionmgr/story/model/apply_mutations.cc
index 21c5b11..d0308ee 100644
--- a/bin/sessionmgr/story/model/apply_mutations.cc
+++ b/bin/sessionmgr/story/model/apply_mutations.cc
@@ -6,6 +6,8 @@
 
 #include "peridot/bin/sessionmgr/story/model/apply_mutations.h"
 
+#include "lib/fostr/fidl/fuchsia/modular/storymodel/formatting.h"
+
 using fuchsia::modular::StoryVisibilityState;
 using fuchsia::modular::StoryState;
 using fuchsia::modular::storymodel::StoryModel;
@@ -38,9 +40,8 @@
       case StoryModelMutation::Tag::kSetRuntimeState:
         ApplySetRuntimeState(command.set_runtime_state(), &new_model);
         break;
-      default:
-        FXL_LOG(FATAL) << "Unsupported StoryModelMutation: "
-                       << fidl::ToUnderlying(command.Which());
+      case StoryModelMutation::Tag::Invalid:
+        FXL_LOG(FATAL) << "Encountered invalid StoryModelMutation: " << command;
     }
   }